Storage stability of tetrakis nickel compounds

ABSTRACT

The storage stability of tetrakis nickel compounds, such as tetrakis (triorganophosphite) nickel compounds, can be increased by storing said compounds under a protective blanket selected from alcohols and aliphatic hydrocarbons.

United States Patent Levine [4 1 June 13, 1972 [54] STORAGE STABILITY OFTETRAKIS 3,414,629 12/1968 McCall et al. ..260/666 NICKEL COMPOUNDSFOREIGN PATENTS OR APPLICATIONS 72 I t: RalhLei F hld,N.J. nven or p vne, f 0 716,072 8/1965 Cana [73] Assignee: Cities Service Company, NewYork, NY.

R Tl N [22] Filed: Dec. 4, 1970 OTHE PUBLICA O s V al.l 3 1964.1062-1063 pp No: 95,325 mal et norgamc Chemistry )p PrimaryExaminer-Tobias E. Levow [52] us. Cl. ..260/439 R, 252/431 PAssislantExaminerA- D me [5 I Int. Cl. ..C07f 75/04 y-J Richard Geaman[58] Field of Search ..260/439 R; 252/431 P ABSTRACT [56] ReferencesCited The storage stability of tetrakis nickel compounds, such as UNITEDSTATES PATENTS tetrakis (triorganophosphite) nickel compounds, can beincreased by storing said compounds under a protective blanket 3,152,15810/ 1964 Clark ..260/439 R l d f l hol and aliphatic hydrocarbons.3,243,468 3/1966 Clark et a1. ..260/666 3,328,443 6/1967 Clark et al..260/439 R 6Claims, No Drawings STORAGE STABILITY OF TETRAKIS NICKELCOMPOUNDS BACKGROUND OF THE INVENTION This invention relates to a methodfor improving the storage stability of tetrakis nickel compounds. Moreparticularly this invention relates to a method for improving storagestability of tetrakis (triorganophosphite) nickel compounds.

It is known that an organonickel compound can be reacted with atriorganophosphorous compound to yield a tetrakis (triorganophosphite)nickel compound, which can be precipitated and recovered as a solidproduct, useful as a polymerization catalyst. It has been found thatupon storage, the tetrakis nickel compounds tend to decompose badlyafter periods of more than a few days, even when stored under a blanketof nitrogen.

SUMMARY OF THE INVENTION It has now been found that solid tetrakis(triorganophosphite) nickel compounds, contaminated with residualtriorganophosphite compounds, can be stored for extended periods of timewhen stored in a protective atmosphere selected from alcohols andaliphatic hydrocarbons.

In the preparation of a tetrakis (triorganophosphorous) nickel compound,such as described and claimed in US. Pat. Nos 3,152,158 and 3,328,443, anickel compound can be reacted with a triorganophosphorous compound, andthe reaction product comprising complexed zerovalent nickel can beprecipitated by pouring the mixture into an inert non-solvent. Theprecipitated product can be recovered by filtration and is useful as acatalyst. US. Pat. No. 3,243,468 describes and claims the use of suchtetrakis nickel compounds in the polymerization of various monomers,such as butadiene.

The tetrakis (triorganophosphite) nickel compounds prepared as describedabove have been found to be quite sta ble in a completely pure state. Ithas further been found that when contaminated with relatively smallamounts of residual triorganophosphite compounds, the tetrakis nickelcompounds tend to be quite unstable during storage, starting todecompose almost immediately, for example within an hour, even whenstored under a blanket of nitrogen. One way of obviating or overcomingthis problem is to work up and purify the tetrakis nickel compounds to apoint that there is no remaining residual triorganophosphite materialleft as a contaminant. Unfortunately however, this procedure is timeconsuming and expensive and yields no real benefit since the presence ofsmall amounts of triorganophosphite material does not effect the utilityof the tetrakis (triorganophosphite) nickel compounds as polymerizationcatalysts. As an alternative to the scrupulous scrubbing of the tetrakisnickel compounds to remove all trace of triorganophosphorouscontaminants, it has been found that storage stability of the solidtetrakis (triorganophosphorous) nickel compounds can be improved bystoring the material in accordance with this inventron.

Broadly, the improved storage stability can be obtained by storingtetrakis (triorganophosphate) nickel, which is contaminated withtriorganophosphite, under a protective blanket consisting essentially ofan inert non-solvent for said tetrakis (triorganophosphite) nickel. Asused herein, the term nonsolvent" refers to compounds which willdissolve less than about 1 percent by weight of the tetrakis(triorganophosphorous) nickel compound while the term solvent" is meantto include compounds in which more than about 1 percent by weight of thetetrakis nickel compounds are soluble. Characteristics of thenon-solvents which are useful in the scope of this invention are thatthey be appreciably miscible with triorganophosphorous contaminant butthat the tetrakis nickel product be insoluble therein. Anothercharacteristic of the non-solvent is that it be easily and substantiallycompletely removable from the stored product. Thus, generally, anonsolvent having a low viscosity is more desirable than one having ahigh viscosity. Volatility is another factor to be considered inchoosing a non-solvent. Since the tetrakis nickel product is generallystored at ambient temperature, the nonsolvent vapor pressure isdesirably not excessive at these temperatures. Broadly, the boilingpoint of the non-solvent can range from about 20 C. to about 300 C. witha preferred range of from about 50 to about 200 C. The non-solvent willof course be inert with respect to both the reactants and the productsand be inert to the surrounding atmosphere. Since this atmosphere isusually air, the non-solvent is desirably not readily oxidized underambient conditions when the storage container is opened, as for examplefor the periodic removal of portions of the tetrakis nickel compounds.

As indicated above, the alcohols are a preferred class of non-solvents.The alcohols can be primary, secondary or tertiary, and can bemonohydric or polyhydric. Preferred alcohols are alkanols having up toabout 14 carbon atoms and include for example methanol, ethanol,propanol-l, 2-methylpropanol-l, butanol-l, pentanol-l, 2-ethyl-butanol-lcyclohexanol, octanol-l, dodecanol-l, ethylene glycol and triethyleneglycol. Liquid alkanols are especially preferred. Mixtures of thesealcohols can also be used. Insofar as the liquid alkanols arecommercially available and inexpensive, they are especially preferred.

In addition to the alcohols, it has been found that alkanes are anotherpreferred class of non-solvents. The preferred saturated aliphatichydrocarbons are those which are liquid at ambient temperature. Thus,generally, those saturated aliphatic hydrocarbons having from about fiveto about 14 carbon atoms are preferred with the c to c, hydrocarbons,such as hexane or heptane, being particularly preferred. The saturatedaliphatic hydrocarbons can be used either alone or in combination withother saturated aliphatic hydrocarbons and can be either straight orbranched chain.

As a general proposition, hydrocarbons other than the saturatedaliphatic hydrocarbons, oxygenated hydrocarbons other than the alcoholsand alcohol ethers, halogenated hydrocarbons, heterocyclic compounds,aromatic hydrocarbons, etc., can be classified as solvents for thetetrakis nickel compound and are not useful under the conditions setforth herein. These latter compounds can be used as recrystallizationsolvents, if recrystallization is needed or desired for the crudetetrakis nickel compound. Solvents are not desirable agents forcontacting the tetrakis nickel compounds in storage insofar as it hasbeen found that a solution of the tetrakis nickel compound, when exposedto even traces of air or oxygen, decomposes rapidly in a very shorttime.

The process of this invention is useful regardless of the structure ofthe triorganophosphite contaminant or the triorganophosphite ligand inthe nickel complex. Examples of wellknown and useful phosphitecontaminants and ligands include tri(2-ethyl-hexyl) phosphite,tri(p-methyoxyphenyl) phosphite, triphenylphosphite, trioctylphosphite,triethylphosphite and tn'( methoxymethyl) phosphite.

One method of precipitating the tetrakis nickel compound from thereaction mixture and thereafter storing it, is to use one non-solvent asa precipitant and another non-solvent as the atmosphere to store thefiltered product. The preferred practice, however is to use the samenon-solvent for both functions. This, of course, avoids theinconvenience and cost of multiple steps. When the tetrakis nickelcompound is isolated from its reaction mixture, as by precipitationusing an inert non-solvent, the isolation can be carried out in anyconvenient manner, such as by filtration using known and acceptedmethods and equipment. The isolated product, in the form of a filtercake, can be washed with a fresh portion of the non-solvent. While notessential, this is a desirable inter mediate step insofar as it isuseful to remove at least part of the triorganophosphite contaminantfrom the precipitated tetrakis nickel compound. Additional filtrationcan, of course, be used to remove the wash liquid.

The quantity of non-solvent used as an atmosphere to protect theisolated tetrakis nickel compounds is broadly that amount needed toeffectively shield the product from an oxidizing atmosphere. Since thecatalyst product is substantially insoluble in the non-solvent, a largeexcess of non-solvent can be used. There is, however, no significantbenefit to be derived from the use of a large excess and, in fact, it ispreferred to use that amount of non-solvent which just covers thesurface of the product.

It has been found that moisture frequently can be a contributing factorto the decomposition of the catalyst and it is therefore desirable tomaintain a low level of moisture in the stored product and its immediateatmosphere. This can be conveniently accomplished by using a productprepared under conditions minimizing contact with atmospheric moisture,

I methanol, washing several times with methanol and drying atrecrystallized by dissolving in benzene, precipitating in such by usingan anhydrous non-solvent and by storing the BLE 2 tetrakls nickelcompound together with the non-solvent in a substantially airtightcontainer Days of Open Storage N1 *Concentration %Deeompos1t1onDESCRIPTION OF THE PREFERRED EMBODIMENTS 3 5 33 ppm L2 5 1042 ppm 2.3EXAMPLE I 7 1567 ppm 3.5 2o 11 17,100 ppm 1.71% 38 Tetrakls(triphenylphosphite) nickel was prepared according to the followingmethod: nickel acetylacetonate dihydrate (21.76 lbs., 0.0745 mole) wasdissolved in benzene (161.25 The percent decomposition was calculated onthe basis that lbs.), and the solution was azeotropically distilled toremove the tetrakis nickel catalyst contained 4.51 percent nickel. ltwater. The resultant solution was used. Triphenylphosphite Can be Seenfrom the above that aflfi! eleven y Of p (94.6 lbs., 0.305 mole) wasadded, with mild agitation. The storage there has been substantial andsignificant decomposi temperature of the mixture was 8 C. Triethylaluminum {ion- (18.75 lbs., 0.165 mole) in 75 lbs. dry benzene wasadded, EXAMPLE m with mild agltation, over a period of about one hour.During this addition period, the reaction temperature was allowed to Avaflety of llqmd Organic compounds was tested for p rise to 1 1 Then,over a period f 30 minutes the reactor tective activity toward thetetrakls n1ckel compound by the temperature was raised to 40 C. Thereactor contents were followmg Procedure: poured, over a period of 30minutes, into a tank containing In a 1 glass b fitted i h a screw cap,was placedl 401 lbs. of methanol. A precipitate of tetrakis(triphenylphosgram of the ten-abs (mphelwiphosphte) mckel' m phite)nickel was formed The product was separated by a Examplelabove, togetherwrth 0.1 ml. triphenylphosphite and centrifuge filter, and thealcohol-wet filter cake was removed 2 of the test l mdcated The i samplefrom the centrifuge The cake was Smmed with additional bottles wereopened twice a week, and the following visual obmethanol, and themixture was filtered. The washed and fil- Servanons were madeassummanzedm Table 3 below tered product was then air-dried and storedin a polyethylene 40 TABLE 2 \mdm' a dry nitrogen atmosphere- The P wasa Test Liquid Observed sample Observed sample white powder. The productobtained above was determined to color after 2 wks. color after besubstantially free of triphenylphosphite. The following 5 evaluationswere performed: tetrakis nickel catalyst prepared above (10 grams) wasplaced in clean 4 oz. flint glass bottle, 212 equipped with a screw cap,and was treated with various addi- 222 whit: Wme tives. All testspec1mens were per1od1cally opened to the atlq white White mosphere.Bottle 1 contained 0.5 ml. water; bottle 2 cony 'p p White l tained 0.5ml. water plus I ml. triphenylphosphite; bottle 3 fgg ftg contained 1ml. triphenylphosphite; bottle 4 contained 20 ml. cycloiexanol white wmethanol; and bottle 5 contained 20 ml. methanol plus 1 ml. Ethyleneglycol White White triphenylphosphite. The capped bottles were openedthree Lnahylene glym as? times a week to assure an adequate exposure toair and oxsfi f Ligplnecimy Light Grey ygen. V1sual exammations weremade at the end of two weeks acetate white Grey and at the end of fourweeks. The results are shown in Table l. Acetone p @9 TABLE 1Description of bottle contents Bottle Additive At start After 2 weeksAfter 4 Weeks 1 Water White solid White. solid White solid.

Water plus trlphenylphosphite do Greenlsh paste. Yellow-green paste.Triplienylphosphite d0 Light green solid Yellow-green solid.yetnanolnnflnnl. no.1. .fi. .H down Whitlo solid, with faint supernatantliquid. White solid, with faint supernatant liquid. 5 let ano plusti'ipienyp osp itm. .(o (0 Do.

i iteeiiheseen rrtinitiiebiei tiits that tier. was essentially gy 'e ytA Light Green Green no difference between the results obtained withmethanol and gii zg igg'g 2:3 gl i methanol plus triphenylphosphite.Water, on the other hand, in tetrachloride orange Orange connection withtriphenylphosphite, yielded very poor results. Dimethyl sulfoxide WhiteLight Green Dimethyl formamide Light Green Light Green Dark EXAMPLE llPyridine Brown Brown Liquid Aniline Grey-Green Dark Green BenzeneGreen-Brown Green-Brown A portlon of the product prepared in Example Iwas 5 lyscycloocladiene Brown Brown Pam vent is selected from alcoholsand saturated aliphatic hxdwsar q sr. V V w 7 3. A method according toclaim 1 in which the alcohols are primary and have a chain length offrom one to about 14 carbon atoms.

4. A method according to claim 1 in which the aliphatic hydrocarbonshave a chain length of from about five to about 14 carbon atoms.

5. A method according to claim 1 in which the alcohol is methanol.

6. A method according to claim 1 in which the aliphatic hydrocarbon ishexane.

II I I! l l

2. A method according to claim 1 in which the inert non-solvent isselected from alcohols and saturated aliphatic hydrocarbons.
 3. A methodaccording to claim 1 in which the alcohols are primary and have a chainlength of from one to about 14 carbon atoms.
 4. A method according toclaim 1 in which the aliphatic hydrocarbons have a chain length of fromabout five to about 14 carbon atoms.
 5. A method according to claim 1 inwhich the alcohol is methanol.
 6. A method according to claim 1 in whichthe aliphatic hydrocarbon is hexane.